3,154 research outputs found
Performance of a First-Level Muon Trigger with High Momentum Resolution Based on the ATLAS MDT Chambers for HL-LHC
Highly selective first-level triggers are essential to exploit the full
physics potential of the ATLAS experiment at High-Luminosity LHC (HL-LHC). The
concept for a new muon trigger stage using the precision monitored drift tube
(MDT) chambers to significantly improve the selectivity of the first-level muon
trigger is presented. It is based on fast track reconstruction in all three
layers of the existing MDT chambers, made possible by an extension of the
first-level trigger latency to six microseconds and a new MDT read-out
electronics required for the higher overall trigger rates at the HL-LHC. Data
from -collisions at is used to study the
minimal muon transverse momentum resolution that can be obtained using the MDT
precision chambers, and to estimate the resolution and efficiency of the
MDT-based trigger. A resolution of better than is found in all sectors
under study. With this resolution, a first-level trigger with a threshold of
becomes fully efficient for muons with a transverse momentum
above in the barrel, and above in the
end-cap region.Comment: 6 pages, 11 figures; conference proceedings for IEEE NSS & MIC
conference, San Diego, 201
Precision Drift Chambers for the Atlas Muon Spectrometer
ATLAS is a detector under construction to explore the physics at the Large
Hadron Collider at CERN. It has a muon spectrometer with an excellent momentum
resolution of 3-10%, provided by three layers of precision monitored-drift-tube
chambers in a toroidal magnetic field. A single drift tube measures a track
point with a mean resolution close to 100 micron, even at the expected high
neutron and gamma background rates. The tubes are positioned within the chamber
with an accuracy of 20 microns, achieved by elaborate construction and assembly
monitoring procedures.Comment: 3 pages, 2 eps figures, Proceedings for poster at Physics in
Collisions Conference (PIC03), Zeuthen, Germany, June 2003. FRAP1
Large-Scale Production of Monitored Drift Tube Chambers for the ATLAS Muon Spectrometer
Precision drift tube chambers with a sense wire positioning accuracy of
better than 20 microns are under construction for the ATLAS muon spectrometer.
70% of the 88 large chambers for the outermost layer of the central part of the
spectrometer have been assembled. Measurements during chamber construction of
the positions of the sense wires and of the sensors for the optical alignment
monitoring system demonstrate that the requirements for the mechanical
precision of the chambers are fulfilled
Upgrade of the ATLAS Muon Trigger for the SLHC
The outer shell of the ATLAS experiment at the LHC consists of a system of
toroidal air-core magnets in order to allow for the precise measurement of the
transverse momentum p of muons, which in many physics channels are a
signature of interesting physics processes. For the precise determination of
the muon momentum Monitored Drift Tube chambers (MDT) with high position
accuracy are used, while for the fast identification of muon tracks chambers
with high time resolution are used, able to select muons above a predefined
p threshold for use in the first Level of the ATLAS triggering system
(Level-1 trigger). When the luminosity of the LHC will be upgraded to 4-5 times
the present nominal value (SLHC) in about a decade from now, an improvement of
the selectivity of the ATLAS Level-1 triggering system will be mandatory in
order to cope with the maximum allowed trigger rate of 100 kHz. For the Level-1
trigger of the ATLAS muon spectrometer this means an increase of the p
threshold for single muons. Due to the limited spatial resolution of the
trigger chambers, however, the selectivity for tracks above ~20 GeV/c is
insufficient for an effective reduction of the Level-1 rate. We describe how
the track coordinates measured in the MDT precision chambers can be used to
decisively improve the selectivity for high momentum tracks. The resulting
increase in latency will also be discussed.Comment: These are the proceedings of a presentation given at the Topical
Workshop of Electronics for Particle Physics 2010 in Aachen, Germany (sept.,
20-24, 2010
Performance of the ATLAS Precision Muon Chambers under LHC Operating Conditions
For the muon spectrometer of the ATLAS detector at the large hadron collider
(LHC), large drift chambers consisting of 6 to 8 layers of pressurized drift
tubes are used for precision tracking covering an active area of 5000 m2 in the
toroidal field of superconducting air core magnets. The chambers have to
provide a spatial resolution of 41 microns with Ar:CO2 (93:7) gas mixture at an
absolute pressure of 3 bar and gas gain of 2?104. The environment in which the
chambers will be operated is characterized by high neutron and background with
counting rates of up to 100 per square cm and second. The resolution and
efficiency of a chamber from the serial production for ATLAS has been
investigated in a 100 GeV muon beam at photon irradiation rates as expected
during LHC operation. A silicon strip detector telescope was used as external
reference in the beam. The spatial resolution of a chamber is degraded by 4 ?m
at the highest background rate. The detection efficiency of the drift tubes is
unchanged under irradiation. A tracking efficiency of 98% at the highest rates
has been demonstrated
Performance of the ATLAS Muon Drift-Tube Chambers at High Background Rates and in Magnetic Fields
The ATLAS muon spectrometer uses drift-tube chambers for precision tracking.
The performance of these chambers in the presence of magnetic field and high
radiation fluxes is studied in this article using test-beam data recorded in
the Gamma Irradiation Facility at CERN. The measurements are compared to
detailed predictions provided by the Garfield drift-chamber simulation
programme
A novel approach to track finding in a drift tube chamber
A novel track finding approach for drift tube detectors
Development of Muon Drift-Tube Detectors for High-Luminosity Upgrades of the Large Hadron Collider
The muon detectors of the experiments at the Large Hadron Collider (LHC) have
to cope with unprecedentedly high neutron and gamma ray background rates. In
the forward regions of the muon spectrometer of the ATLAS detector, for
instance, counting rates of 1.7 kHz/square cm are reached at the LHC design
luminosity. For high-luminosity upgrades of the LHC, up to 10 times higher
background rates are expected which require replacement of the muon chambers in
the critical detector regions. Tests at the CERN Gamma Irradiation Facility
showed that drift-tube detectors with 15 mm diameter aluminum tubes operated
with Ar:CO2 (93:7) gas at 3 bar and a maximum drift time of about 200 ns
provide efficient and high-resolution muon tracking up to the highest expected
rates. For 15 mm tube diameter, space charge effects deteriorating the spatial
resolution at high rates are strongly suppressed. The sense wires have to be
positioned in the chamber with an accuracy of better than 50 ?micons in order
to achieve the desired spatial resolution of a chamber of 50 ?microns up to the
highest rates. We report about the design, construction and test of prototype
detectors which fulfill these requirements
Resolution and Efficiency of the ATLAS Muon Drift-Tube Chambers at High Background Rates
The resolution and efficiency of a precision drift-tube chamber for the ATLAS
muon spectrometer with final read-out electronics was tested at the Gamma
Irradiation Facility at CERN in a 100 GeV muon beam and at photon irradiation
rates of up to 990 Hz/square cm which corresponds to twice the highest
background rate expected in ATLAS. A silicon strip detector telescope was used
as external reference in the beam. The pulse-height measurement of the read-out
electronics was used to perform time-slewing corrections which lead to an
improvement of the average drift-tube resolution from 104 microns to 82 microns
without irradiation and from 128 microns to 108 microns at the maximum expected
rate. The measured drift-tube efficiency agrees with the expectation from the
dead time of the read-out electronics up to the maximum expected rate
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